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W. A. RHODES AND F. E. ANDERSON. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED SEPT. 30, 1916.

1,387, 18 1 v PatentedAug. 9, 1921 W/W/dm A. fi hades n tes tates PATENT orrlcii.

WILLIAM A. RRonEs, on NEW Yo R, N. Y., AND FREDERICK E. ANDERSON, or

NEWARK, NEW .IERsEY, ASSIGNORS To WESTERN ELEoTRIc COMPANY, INcoR- PQRATED, OF NEW YORK, N. Y., A coREoRATIoN on NEW YORK. V

TELEEHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Application filed September 30, 1918. Serial No. 256,272.

To all whom it may concern.

Be it known that we, WILLIAM A. RHODES and FREoERIoK-E. ANnEnsoN, citizens of the United States, residing at New York, in the county of New York and State of New York, and at Newark, in the county of Essex and State of New Jersey, respectively, have invented certain new and useful Improvements in Telephone-Exchange Systems, of

which-the following is a full, clear, concise, and exact description.

This invention relates to telephone exchange systems and more particularly to such systems employing trunk circuits extending from operators positions of the switchboard to chief operators desks, information and supervisory positions and like positions.

The object of this invention is to provide in such system improved means for establishing communication between the desk operator and the switchboard operator.

In accordance with this invention a trunk.

circuit extending from a switchboard position to an information operators desk, is provided with switching apparatus at the desk end, by means of which, while the desk operator is connected with the trunk circuit, electromagnetic switching mechanism in the trunk circuit may be operatively controlled to connect the desk operators telephone-set with a circuit directly connected with the switchboard telephone set. 1

For a more complete understanding of this invention, reference should be iad to the following description, considered in connection with the accompanying drawing illusrating one embodiment thereof.

[is shown in the drawinga telephone line A extends to and terminatesat an operators position of a switchboard. A trunk circuit Cextends from the operators position of the switchboard to an information desk, at which is located a cord circuit D adapted for connection in the trunk circuit C. A cord circuit B located at the switchboard may be employed to connect the teleof the operation of the system shown in the drawings. it will be so described;

Patented Aug. 9, 1921..

Subscriber A ininitiating a call removes y the receiver from the switchhook, thereby causing the operation of line relay 6 and the I lighting of line lamp 7. 'The operator, at

whose position the line terminates, observing the lighted condition of the line lamp 7, inserts answering plug 8 of the cord. circuit B into line jack 9, thereby causing operation of cutoff relay 10' over a circuitfrom battery through answering lamp 11, resistance 12, sleeve contacts of the answering plug '8 and the jack 9' and the winding ofcutoff relay 10 to ground. Cutoff relay 10 in operating disconnects the line relay 6 from the line, thereby extinguishing the line lamp 7. Answering supervisory relay 13 is operated overthe telephone line upon the connection ofv the answering plug therewith, and in operating connects a shunt circuit. including resistance 14 about the lamp 11, thereby extinguishing lamp. In fact the energization of the answering susupervisory pervisory relay 13 follows so soon after the insertion of the plug 8 into the jack 9 that the answering supervisory lamp ll'does not have time to be fully illuminated before being shunted by the resistance 14.

The operator maynow actuate listening 24 is thereupon lighted over. a circuit from 7 battery through" the lamp 24, resistance 25, sleeve contacts of the plug 22 and jack 23 and resistance 26, to ground. The operator may now actuate ringing key 27 to connect ringing current with the trunk circuit C to cause the energization of relay28. Relay28 upon being energized establishes a locking circuit foritself which may be traced from battery through the contact and right-hand winding of the relay 28 and the contact of relay 29 to ground. Lamp 30 associated with the incoming end of the trunk circuit C and located at the information desk is lighted upon the energizatio'n ofv the re.- lay 28.

The information operator upon observing the lighted condition of the lamp 30, insertsplug 31 of the cord circuit D into jack 32 of the trunk circuit C. Relay 29 thereupon operates over a circuit from ba tery through high resistance 33, sleeve contacts of the plug 31 and the jack 32 and the windings of relays 34; and 29 to ground. Relay 29 opens the locking circuit of relay 28, which thereby releases its armature and extinguishes the lamp 30. Relay 34: is marginal, so that when included in circuit with the high resistance 33, it does not operate, but it does operate when a low resistance 35 is included in parallel with the high resistance 33, as will more fully hereinafter appear. Calling supervisory relay 39 of the cord circuit B also operates when the plug 31 is inserted into the jack 32, the circuit therefor being from battery through the winding of the relay 39, the lower normal contact of ringing key 27, ring contacts of the plug 22 and the jack 23, lower normal contact of the relay 34:, ring contacts of the jack 32 and the plug 31, coil 38, tip contacts of the plug 31 and the jack 7 the upper normal contact of the relay 34-, tip contacts of the jack 23 and the plug 22 and the upper normal contact of ringing key 27 to ground. Relay 39 in operating establishes a shunt circuit including .resistance 37 about the lamp 24 which is thereby extinguished. The information operator may now actuate listening key 36 to connect the telephone set 37 with the cord circuit D and is thereby in direct communication with the calling subscriber A. If the calling subscriber A desires information as to the number of the telephone line 'of a particularly named subscriber, this information can be furnished by the information operator, who after supplying the information may wish to communicate with the switchboard operator for the purpose of requesting this operator to establish connection between line A and the desired line.

l-leretofore, the scheme employed for enabling the information operator to communicate with the switchboard operator contemplated the repeated opening and closing of the trunk circuit, thereby to cause the intermittent operation of the calling supervisory lamp of the connected cord circuit at the switchboard, which served as a signal to the switchboard operator. The switchboard operator would then actuate the listening key connecting the telephone setwith the talking circuit and would thereby be in communication with the desk operator. This repeated opening and closing of the talking circuit results in the production of disagreeable clicks in the receivers of the calling subscriber and the desk operator, which it is desirable to avoid.

In systems heretofore employed the con- 1,ss7,1s1

nection between the information and switch board operators has been established 'by way of a separate cord circuit which cooperated with a jack ended circuit connected directly with the switchboard operators telephone set. In such systems, when the information operator desired to communicate with the switchboard operator, it was necessary first to actuate a holding key and restore the listening key of the connected cord circuit and then to connect the separate cord circuit with the jack ended circuit and actuate the listening key of the separate cord circuit.

In accordance with the present invention, means are provided for establishing telephonic communication between the two operators without employing a separate cord and jack and also without producing the disagreeable and severe clicks to the calling subscriber and the desk operator. .This is brought about in the following manner: The desk operator, desiring to communicate with switchboard operator, actuates key 40, thereby including the low resistance 35 in parallel with the high resistance 33. Relay 3% thereupon immediately operates and first connects bridging impedance coil 41 across the tip and ring conductors of the trunk circuit U to prevent the deenergization of the calling supervisoryrelay 39. Relay 34 next opens its normal contacts, disconnecting the incoming or desk end of the trunk C from the outgoing or switchboard end thereof and then closes its middle and lower alternate contacts, thereby connecting the incoming or desk end of the trunk circuit C with conductors a2 and 43, which are connected with the switchboard operators telephone set 21. The desk operator may thereupon communicate the needed information to the switchboard operator, who may then withdraw the plug 22 from the jack 23 and complete the desired communication. The desk operator mayvthen release the key 40 and listening key 36 and withdraw the plug 31 from the jack 32 whereupon all apparatus associated with the trunk circuit C and the cord circuit A is restored to normal ,position.

Relay as is so constructed that its upper alternate contact is closed before the other alternate contacts and before normal contacts are opened, whereby the impedance coil ll is connected across the talking circuit before this talking circuit is broken, thereby preventing any change in current distribution in the talking circuit. Therefore, no appreciable click is produced in the receiver of the calling subsciber, when the desk operator actuates key 40 to communicate with the switchboard operator.

What is claimed is: V

1. A telephone exchange system comprising a trunk circuit including a pair of talking conductors extending from a first to a second switchboard, a calling telephone line between the telephone set and the calling telephone line, an operators telephone set at the first switchboard, a switch at the second switchboard, and means in the trunk circuit responsive to the actuation of the switch to establish a circuit including the two operators telephone sets.

2. A telephone exchange system comprising a trunk circuit including a pair of talking conductors extending from a first to a second switchboard, a calling telephone line terminating at the first switchboard, alink circuit thereat connecting the calling telephone line with the trunk circuit, an operators telephone set at the second switchboard, means for connecting the operators telephone set with the talking conductors thereby establishing a telephonic connection between the telephone set and the calling telephone line, an op-erators telephone set at the first switchboard, a switch at the second switchboard, and a relay in the trunk circuit energized upon the actuation of the switch to establish a circuit including the two operators telephone sets.

3. A telephone exchange system comprising a trunk circuit including a pair of talking conductors extending from a first to a second switchboard, a calling telephone line terminating at the first switchboard, a link circuit thereat connecting the calling telephone line with the trunk circuit, an operators telephone set at the second switchboard, means for connecting the operators telephone set with the talking conductors thereby establishing a telephonic connection between the telephone set and the callingtelephone line, a pair of conductors extending from the first switchboard to the second switchboard, an operators telephone at the first switchboard connected with the pair of conductors, a switch at the second switchboard, and means in the trunk circuit responsive to the actuation of the switch to connect the operators telephone set of the second switchboard with the pair of conductors.

4:. A telephone exchange system comprising a trunk circuit including a pair of talking conductors extending from a first to a second switchboard, a calling telephone line terminating at the first switchboard, a link circuit thereat connecting the calling telehone line with the trunk circuit, an operators telephone set at the second switchboard, means for connecting the operators telephone set with the talking conductors thereby establishing a telephonic connection between the telephone set and the calling telephone line, a pair of conductorsextend ing from the first switchboard to the sec.

0nd switchboard, an operators telephone set at the first switchboard connected with the pair of conductors, a switch at the sec- 0nd switchboard, and a .relay in the trunk circuit energized upon the actuation of the switch to connect'the operators telephone set of the second switchboard with the pair of conductors. a

5. A telephone exch ange system comprising a trunk circuit including a pair of talk- 7 ing conductors extending from a first to a second switchboard, a calling telephone line terminating at the first switchboard, a link circuit thereat connecting the calling telephone with the trunk circuit, an operators telephone set at the second switchboard, means for connecting the operators telephone set with the talking conductors thereby establishing a telephonic connection between the telephone set and the calling telephone line, a pair of conductors extend ing from the first switchboard to the second switchboard, an operators telephone set at the first switchboard connected with the pair of conductors, a switch at the second switchboard, and a relay in: the trunk circuit energized upon the actuation of the switch to disconnect the telephone set of the second switchboard from the calling telephone line and to connect it with the pair of conductors.

6. A telephone exchange system comprising a trunk circuit including a pair of talking conductors extending from a first to a second switchboard, a calling telephoneline terminating at the first switchboard, a link circuit thereat connecting the calling tele-' the signal control relay established when the operators telephone set is connected with the talking conductors, a pair of conductors extending from the first to the second switchboard, an operators telephone set at the first switchboard connected with the pair of conductors, a switch at the second switchboard, a relay energized upon the actuation of the switch to disconnect the telephone set of the second switchboard from the calling telephone line and to connect it with the pair of conductors, and a circuit established "upon, the energization of the second relay for maintaining the signal control relay energized. c i i 7 In a telephone exchange system comprising a trunk circuit including a pair of talking conductors extending from a first to a second switchboard.

ling the connection of the bridging coil, a signal. associated with the trunk circuit, second relay in circuit association with said marginal relay for controlling said signal, and means associated with said second link circuit for controlling said marginal relay. In witness whereofll hereunto subscribe my name this 19th day of August, 1918.

WILLIAM A. RHODES. In witness whereof, I hereunto subscribe my name this 25th day of September, 1918.

FREDERICK E. ANDERSON. 

